Viral TRAP RNAseq Data from Ipsilateral and Contralateral Corticospinal Neurons in Mouse

The spinal cord receives inputs from the cortex via corticospinal neurons (CSNs). While predominantly a contralateral projection, a less-investigated minority of its axons terminate in the ipsilateral spinal cord. We analyzed the spatial and molecular properties of these ipsilateral axons and their post-synaptic targets in mice and found they project primarily to the ventral horn, including directly to motor neurons. Barcode-based reconstruction of the ipsilateral axons revealed a class of primarily bilaterally-projecting CSNs with a distinct cortical distribution. The molecular properties of these ipsilaterally-projecting CSNs (IP-CSNs) are strikingly similar to the previously described molecular signature of embryonic-like regenerating CSNs. Finally, we show that IP-CSNs are spontaneously regenerative after spinal cord injury. The discovery of a class of spontaneously regenerative CSNs may prove valuable to the study of spinal cord injury. Additionally, this work suggests that the retention of juvenile-like characteristics may be a widespread phenomenon in adult nervous systems. This TRAP sequencing data was used to determine the molecular similarity to regenerating and embryonic CSNs. Overall design: To determine the molecular characteristics of ipsilateral and contralateral CSNs, we used retrograde viral TRAP in CSNs and sequenced both input mRNA and TRAP immunoprecipitated RNA from 5 paired biological replicates of three animals each